Prolongations of the Fundamental Structure (Neighbour Note)
The neighbour note is one of the most common diminutions, but there are some neighbour note prolongations of the fundamental structure that are particularly suitable for further prolongation into large spans of music. The only neighbour notes that fit this criteria are upper neighbour notes to and . In the example below, the neighbour note could give rise to a piece of music in three sections - an initial section in the tonic, a middle one in the subdominant and a return of the first section with a final cadence in the tonic.

An example of this prolongation lying behind a short section of music can be found here

Note that a lower neighbour note to is not exactly forbidden, but is better explained as an interruption.